1.   At a rough estimate, staff are recycling less than a quarter of the paper we buy.

2.   Can you give me a rough estimate of how much the repairs will cost?

3.   This proposal represents a rough estimate of the cost of materials and labor.

4.   We were only able to make a rough estimate of how much fuel would be required.

5.   Rough estimates of cost are used to create a priority list of the most promising cases for further study.

6.   You should be able to give a rough estimate of how much work each stage of the case is likely to entail.